Nitrogen cycle nitrification

Interactions of the oxygen and nitrogen cycles Nitrification and denitrification... 

Delwiche, C. C. (1981). The nitrogen cycle and nitrous oxide. In "Denitrification, Nitrification, and Atmospheric Nitrous Oxide" (C. C. Delwiche, ed.). Wiley, New York. 

It is remarkable that the nitrogen cycle employs extreme oxidation-reduction states of nitrogen. Nitrification carries N from 3 to 5, whereas denitrification reduces N from 5+ to 0. A more direct cycle using only redox states of N between... 

The nitrogen cycle entails formation of ammonia by bacterial fixation of N2, nitrification of ammonia to nitrate by soil organisms, conversion of nitrate to ammonia by higher plants, synthesis of amino acids from ammonia by all organisms, and conversion of nitrate to N2 by denitrifying soil bacteria. 

Rudd et al. (24) reported disruption of several processes in the nitrogen cycle during experimental acidification of Lakes 223 and 302S in Ontario s Experimental Lakes Area (ELA). In particular, they reported the inhibition of nitrification. 

Figure 1. A simplified watershed nitrogen cycle, with major pathways (arrows) and their effects on the watershed hydrogen budget (numbers in circles) shown. Circled numbers represent the number of hydrogen ions transferred to the soil solution or surface water ( +1) or from the soil solution or surface water (-l)for every molecule of N03 or NH4 + that follows a given pathway. For example, nitrification follows the pathway for NH4 + assimilation into microbial biomass ( + l) and is leached out as N03 ( + 1), for a total hydrogen ion production of +2 for every molecule of N03 produced.

Henriksen, K., and Kemp, W.M. (1988) Nitrification in estuarine and coastal marine sediments. In Nitrogen Cycling in Coastal Marine Environments. SCOPE (Blackburn, T.H., and Sprensen, J., eds.), pp. 207-249, John Wiley, New York. 

Nitrate, 334-336 Denitrification, 340 Nitric acid, 23 Nitrification, 334 Nitrogen cycle, 326... 

Ward, B. B. (2000). Nitrification and the marine nitrogen cycle. In Microbial ecology of the oceans (Kirchman, ed.). Wiley, New York. p. 427—453. 

Figure 21.1 Microbial nitrogen cycling processes in sedimentary environments on a coral reef (A) nitrogen fixation (B) ammonification (C) nitrification (D) dissimilatory nitrate reduction and denitrification (E) assimilatory nitrite/nitrate reduction (F) ammonium immobilization and assimilation. Adapted from D Elia and Wiebe (1990). Anammox (the anaerobic oxidation of NH4" with NO2 yielding N2 ) is not represented, as it has not yet been shown to occur on coral reefs, but may be found to be important in reef sediments.

Abd Aziz, S. A., and Nedwell, D. B. (1986). The nitrogen cycle of an east coast, U.K. saltmarsh II. Nitrogen fixation, nitrification, denitrification, tidal exchange. Estuar. Coastal Shelf Sd. 22, 689-704. 

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